


Baby Sister

by FlyRobinFly



Series: Like Father, Like Son [6]
Category: Teen Wolf (TV)
Genre: Age Regression/De-Aging, Fluff and Humor, Funny, Good Theo Raeken, Guilty Theo, Malia gets deaged, Malia is his sister, Sadness, Sibling Love, Stiles Stilinski is a Little Shit, Theo Raeken is a Little Shit, Theo cries, Theo is a good big brother, Theo loves his sister, de-aged Malia Tate
Language: English
Status: Completed
Published: 2019-04-18
Updated: 2019-04-18
Packaged: 2020-01-15 20:36:18
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,987
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18506617
Author URL: https://archiveofourown.org/users/FlyRobinFly/pseuds/FlyRobinFly
Summary: “I was trying to tell you to keep it down. He finally got her asleep, asshole.”Theo furrowed his brows looking at Stiles and then the baby. “Where’s my sister?” So yeah. Theo would never admit it but he’d grown extremely protective of Malia. It was almost worse than how he was with Liam.Stiles gestured to the baby and Theo scoffed. “You think this is a joke?”





	Baby Sister

**Author's Note:**

  * For [ilovewolves1316](https://archiveofourown.org/users/ilovewolves1316/gifts).



> This is for Taylor just cause. I luv ya!
> 
> Ps. I know there is no Thiam in this fic, I just put it in the tags because the rest of the series has the tag too

Theo barged into the Animal Clinic, anger fuming off of him. “What happened? Where is she?” Stiles didn’t bother giving him details when he sent Theo a text saying something had happened to Malia. Theo automatically assumed the worst.

“Theo, relax-”

“Is she ok?!” Theo nearly shouted. “You don’t just send me a text saying that something happened to my sister and that you need help because she won’t stop crying. Malia doesn’t cry! Something’s wrong-”

Theo’s words were cut off by the sound of a baby crying. Theo turned to identify the source of the noise and saw Deaton Holding a baby in his arms. Since when did Deaton have a baby?

Stiles glared at Theo. “I was trying to tell you to keep it down. He finally got her asleep, asshole.”

Theo furrowed his brows looking at Stiles and then the baby. “Where’s my sister?” So yeah. Theo would never admit it but he’d grown extremely protective of Malia. It was almost worse than how he was with Liam.

Stiles gestured to the baby and Theo scoffed. “You think this is a joke?”

“No! I’m serious. Malia got turned into a baby,” Stiles assured him. “We were trying to catch that sorcerer that’s been popping up and causing trouble but he got to us first. Turned her into a baby.”

Theo pursed his lips and looked at his sister, his baby sister. Malia was definitely cuter as a baby. But she still sounded awful. “What happened to you?”

“Nothing,” Stiles said a little too quickly for Theo to believe him.

Theo held back a smirk. “What happened?”

“It doesn’t matter,” Stiles said, sputtering out some laughter.

Deaton chuckled, something he rarely does. “Just don’t mention Derek.” And that made Stiles blush very hard.

Theo smirked evilly. “Derek, huh? So uh… why Derek? Are you afraid of him?”

“What did I ever do to you?” Stiles asked Deaton.

Then, as if right on cue, Derek walked in the back door. “Deaton, we could use a hand,” Derek announced before he realized Stiles was in the room. And the awkward tension between the two of them said it all. Stiles must’ve made a move on him last time he saw him and Derek was wary of it.

Theo started laughing. “Ho ho ho. You’re not scared of him. You’re in love with him. Oh my god.” Theo felt an overwhelming sense of satisfaction. “This is great. You are never going to live this down.”

“You two stay here and protect Malia,” Deaton said passing Malia off to Theo who held the baby away from his body like it was some foreign object to be feared. To him is was. And Deaton was joining Derek towards the exit.

Theo looked at the baby and winced before trying to pass it off to Stiles. But Stiles was already shamelessly following his latest crush out the door. “Derek, baby, wait up!”

“No, Stiles. Stay with Theo!”

“Oh. Don’t be such a sourwolf!”

And then Theo heard three doors slam shut and a car peel out the back parking lot. He was stuck babysitting… literally. The satisfaction of he’d gotten over Stiles’ love spell was gone. Now he was overwhelmed by fear and panic because… He knew nothing about babies! “Uh…”

The infant in his hands squirmed and he tensed up doing whatever he could to keep her from rolling out of his hands. She started crying again and Theo groaned. “Ugh. Oh my god. What the hell is wrong with you? It’s not my fault! I don’t know how to take care of a baby.”

She wailed and wailed making his ears ache.

“Oh. So now you cry? You never cried when you were a big person.” The rolled his eyes, annoyed with her crying. Wishing she would just shut up. But then something worried him. Her cries turned into hyperventilating. That wasn’t normal, right? That was something he should panic over right? Cause it made him panic.

He pulled him close to his chest and started rocking her, bouncing his knees. “Hey, Baby Sis. It’s ok. We’re gonna have everything fixed before you know it. I promise.”

And she started to hush, sniffling.

Theo smiled. “There. See? Big brother Theo isn’t so bad, is he?”

She cooed.

“Yeah,” Theo cooed back. “You know I’d do anything to protect you, Sis.”

And that was when Theo realized that Malia was his baby sister and he would do anything to protect her. Sure, he had realized that subconsciously but now he really knew it. And he knew exactly why he felt this way.

After the way he betrayed his other sister, he felt so much guilt. What he did to her turned him into a monster and he didn’t want that to ever happen again. This time he was going to cherish his sister like she was his most prized possession. He was going to protect her like she was a princess even if she acted like she was the furthest thing from it and could protect herself just fine.

He couldn’t let what happened to Tara happened to Malia. He couldn’t lose another sister. “I promise I’ll never make you hate me so much that you haunt me in my dreams.” Theo could never escape the nightmares about Tara. They followed him everywhere making him afraid to sleep and even making him sick sometimes.

But his dreams about Malia were never something he was truly afraid of and he wanted it to stay that way. He’d take the bitching sister with lots of fight in her over the soulless one he’d betrayed any day. “I know I hurt you before but I promise I’ll never do it again,” Theo said, completely unaware that he was crying until a tear fell on Malia’s blanket. He sniffled. “Well, look at that. Now we’ve both cried today. That doesn’t happen very often.”

“I’m sorry I hurt you,” he said. It was unclear whether he was talking about Tara or Malia now. But he pulled her up closer to him face and gave her a kiss on the forehead. “I wish you would forgive me for everything I did to you and your pack.”

“I think she’s more forgiving than she willing to let you believe.”

Theo didn’t look up. He knew it was Peter. He didn’t know how Peter found out though. He sniffed and tried to wipe away the evidence that he had emotions. But it was kinda pointless since Peter had already deemed him the sensitive one.

He heard Peter’s footsteps before he peeked over Theo’s shoulder at his daughter. “Derek called me. Thought you might need help.”

Theo scoffed. “Like you know any more about babies than I do.”

Peter sighed. “I changed Derek’s diapers when I was twelve and thirteen. I used to be a pretty great uncle.”

Theo just glared at him skeptically.

“Look, can I just hold my daughter?”

Theo had the hardest time letting go. How was he supposed to protect her if Peter was holding her? She was so delicate. But Peter cared about her too. He needed to stop being so overprotective.

He sighed, begrudgingly offering Malia to Peter. “Be careful.”

“I’ve held a baby before,” Peter reminded him.

“And none of those babies were my sister,” Theo hissed threateningly.

Peter opened his mouth to correct him but now wasn’t the time to tell Theo he’d met Tara a few times when she was just a little toddler. That would be for when he wasn’t all defensive over Malia.

Malia stirred in Peter’s arms when he took her. He smiled down at her. “Hey, Malia. Wow. Aren’t you just a little ball of cuteness. Definitely cuter than Derek was. He definitely grew into his handsome, ruggedness. But you, darling, you’ve been cute all along.”

Theo watched Peter carefully with his arms crossed. He didn’t like him holding her.

“Huh. Do you think you were this cute when you were a baby?” Peter asked Theo as he bounced her gently yet playfully, light on his feet. “Do you have any pictures?”

Theo shook his head. “I have absolutely no pictures from my childhood.”

“That’s too bad,” Peter said. “Hey. Will you do me a favor and grab my phone from my pocket? I want to document this moment as a father.”

Theo sighed and pulled the phone out from Peter’s back pocket, unlocking it and bringing up the camera. He stepped back ready to take the picture. He felt so ridiculous. Malia was going to be mad about this.

“What are you doing?” Peter said causing Theo to raise an eyebrow in question. “Get in the picture. It won’t be as fun teasing Malia about this if there’s not proof that you were here too.”

Now that made Theo smirk. He loved his sister but he also loved getting a rise out of her. And a picture of Peter and Theo taking care of her as a baby would do just that. Theo stood next to Peter and held the phone out to take some pictures. Never in his life did he ever think he’d find an excuse to take a selfie especially with Peter or Malia. But here he was.

It took a few hours for Scott and the others to return. Scott oogled at baby Malia and took a picture so he could show her what their babies were going to look like. That threw Theo off for a second. “Babies?”

Scott was confused by Theo’s response until he realized that it could be an implication. “Relax, man. I was talking about in the future.”

“Oh,” Theo said, relaxing. When had he tensed up? “Good. Cause that’s my baby sister you’re talking about. Yes, it is,” Theo said booping Malia’s nose. “And she’s not allowed to grow up and have babies. Because she’s just a little baby.”

Theo had gotten so used to talking to Malia like that, he only noticed he’d done it when they all stared at him surprised. Scott tried to bargain. “They’ll call you Uncle Theo.”

Theo thought. “You can get married when you’re twenty and then you can have babies,” he said continuing to talk to her unlike he’s ever talked to anyone else. She was sound asleep and he intended on keeping it that way because she screamed really loud when she was awake. “So, is she stuck like this forever or what?”

“The spell will wear out in a day or two,” Scott said.

“Good,” Theo said. “What about Stiles?” Theo pointed to Stiles off in the corner, making heart eyes at Derek who was very intentionally ignoring Peter who was laughing at them.

“That?” Scott gestured to the man in question. “It’s gonna take a while for the spell to break. Deaton is gonna work on it. But it shouldn’t be a problem as long as Stiles isn’t around Derek and people don’t really mention him.”

“So you chase down any hunters lately?” Stiles asked, trying to be sly but he still owned his usually awkwardness.

Derek just sighed before he lost his patience and banged Stiles’ head against a table, knocking him out. “No one wake him up until we figure out how to fix him. Got it?”

“I’d be happy if he just never woke up,” Theo said only to earn a look from Scott. “I’m kidding. ...sort of.”

“Anyways,” Scott said. “I’m gonna take Malia home with me and my mom and I will take care of her until the spell wears off.”

Theo hesitated. He didn’t want to let go of his baby sister. She was too precious. He wanted to take Malia home with him so he could protect her. But then he smelled it. Unmistakable. Dirty diaper. Theo held her out to Scott. “Here.” As much as he loved his baby sister, he didn’t want to change her diaper.


End file.
